Mr. Justice John Marshall Harlan II did not vote in Presidential elections out of respect for the principle of separation of powers and maintaining political neutrality.
Byron White, despite being a rather conservative jurist, was a lifelong Kennedy Democrat.
Potter Stewart, a mainstream Republican moderate, voted for George McGovern in 1972, out of his dislike for Nixon, whom he came to despise.
I would not be surprised if Anthony Kennedy voted for Gary Johnson.
He also voted for Barry Goldwater, not wanting a Johnson landslide; it’s highly unlikely though that he actually liked Goldwater. He revealed these votes in a 1983 interview with American Heritage (not enough posts to share link).
